Masoni's sixth 3-pointer from five feet beyond the arc gave Cal State Northridge (6-4) a 70-66 lead with 1:20 remaining, and Guay made four free throws to push it to 74-68 lead with 39.1 seconds to go.

UCLA (7-2) pulled to 74-71 on a 3-pointer by Nirra Fields before the Matadors made four free throws down the stretch to snap a five-game winning streak by the Bruins.

It was Cal State Northridge's first victory against a ranked team in its Division I history and its first win against a Pac-12 team since 1996. The Matadors, ranked 19th nationally in 3-point shooting, made 10 of 22 attempts from 3-point range.

Masoni scored 18 points and Randi Freiss had six points and nine rebounds.

Alyssia Brewer scored 14 points for UCLA and Fields had 12. The Bruins committed a season-high 25 turnovers and shot 38.7 percent from the field.

Big West preseason favorite Cal State Northridge, which started four sophomores and a freshman, responded to every UCLA surge in the second half in a game that featured 12 ties and 17 lead changes.

Haley White made 3-pointers to give Northridge leads of 62-58 and 65-62. Masoni's fifth 3-pointer put Northridge ahead, 54-53. Guay scored on a pretty left handed drive before Jianni Jackson converted on a similar play for a 51-49 lead.

UCLA appeared to take control early in the second half when Fields made her fourth 3-pointer to put UCLA ahead, 40-39. But Northridge came out of a timeout, got a stop as Friess fed Guay for a breakaway lay-up.

UCLA took a 33-31 lead into halftime when Markel Walker grabbed a steal fed Mariah Williams for a breakaway lay-up. The Bruins, who average 18.5 turnovers a game, committed 13 in the first half.

Walker was guilty of four of them and scored six points. But Brewer, Fields and Atonye Nyingifa and each scored seven points to keep the Bruins in it through eight ties and eight lead changes.

Guay scored 12 of Cal State Northridge's first 18 points, getting most of them on drives to the basket. Marty Marconi sank three 3-pointers, giving the Matadors leads of 12-6 and 27-26.

UCLA had four turnovers in the first three minutes, and forced coach Cori Close made two substitutions in the opening two minutes.